Querying the physical world

In the next decade, millions of sensors and small-scale mobile devices will integrate processors, memory, and communication capabilities. Networks of devices will be widely deployed for monitoring applications. In these new a pplications, users need to query very large collections of devices in an nd hoc manner. Most existing systems rely on a centralized system for collect ing device data. These systems lack flexibility because data is extracted i n a predefined way. Also, they do not scale to a large number of devices be cause large volumes of raw data are transferred. In our new concept of a de vice database system, distributed query execution techniques are applied to leverage the computing capabilities of devices, and to reduce communicatio n. In this article, we define an abstraction that allows us to represent a device network as a database and we describe how distributed query processi ng techniques are applied in this new context.